Carbon nanotubes are often used in conventional electron sources given their robust physical, chemical and electrical properties. For example, carbon nanotubes (CNTs) generally have high aspect ratios providing a low turn-on field, thereby enabling CNTs to emit electrons well. The CNTs are generally grown on a metal catalyst disposed on a non-metal substrate such as silicon dioxide.
Despite the ability to produce conventional electron sources with CNTs, the functionality of conventional electron sources is limited given the limitations of applying the metal catalyst to the non-metal substrate. For example, it is difficult to apply the metal catalyst in a precise pattern to the non-metal substrate. As such, the spacing of CNT groupings grown on respective regions of metal substrate is often non-uniform and difficult to control, thereby reducing the effectiveness of conventional electron sources. Further, the density of the CNTs in each of the groupings is difficult to control.
Additionally, the process of applying the metal catalyst to the non-metal substrate, e.g., metal catalyst deposition, is relatively expensive. As such, the cost of producing conventional electron sources is increased due to the relatively high cost of applying the metal catalyst to the non-metal substrate.